Alstonic acids A and B, unusual 2,3-secofernane triterpenoids from Alstonia scholaris

2,3-Secofernane triterpenoids, alstonic acids A (1) and B (2), were isolated from leaves of Alstonia scholaris together with an indole alkaloid, N1-methoxymethyl picrinine. Their structures were established from MS and NMR spectroscopic analysis and confirmed by single crystal X-ray diffraction analysis.